scotts8ight

Hey yall, been a while since I have been here but I have a huge problem, well for me anyways. First off just got out of waranty, so I need to see if I can fix this myself. I was at a buddies house helping him move when my backs started spinning. So I tried to kick it into 4 wheel drive. The 4x4 light came on then when I tried to go forward a big clunk came from the transfer and didnt engage. So I put it into park switched the 4h off then switched on 4l light came on tried to go forward and it made a weird whinny clicking sound, and no 4l. I did this several times going back and forth from 4h and 4l and 2 trying to get it to engage, and nothing, followed manual ways to turn it in and out and alas nothing. so I put it into 2 and reverse, then gun it strategy to get out. Now there is one other time when it clunked like this, and they may be related. A month ago I was out at another buddies house and partially got stuck in a corn field. I put it in N and waited for the light to come on, heard a little tunk as it was sliding into 4 wheel then put it in park and gave it some gas, this is when the first clunk acourd, but it did shift into 4h and i got unstuck. My theory is if it is gear drive (Im not sure what is in this transfer, but pretty sure its gears) that I broke a tooth, and the reason why it wont engage now is that the tooth is sitting in between the gears and it wont let the two gears meet, that is unless its plates, then well Im not sure!

2005 F-150 4x4 xlt, It has the 4x4 that you engage with the switch on the dash. 5.4L V8 Automatic.

So the questions I really need answered are:
What does it have in it gears, plates, or what?
Would it be cheaper to buy a new transfer?
Is it fixable?
Any suggestions on what to try?

Any, and I meen any help you can give is really appreciated. If there is a way to identify which transfer it is let me know and I can get that info for you, Im pretty sure there is a number on the case, but as it is night and everything is wet outside, I would rather find it tommorow lol. If there is any other info you need, just let me know. Thanks in advance!
Scott